1. Field of the Invention
The subject invention is directed to spinal implants, and more particularly, to an interspinous process implant with a threaded body and deployable engagement arms for percutaneous placement in the interspinous process space to treat lumbar spinal stenosis.
2. Description of Related Art
The spine consists of a column of twenty-four vertebrae that extend from the skull to the hips. Discs of soft tissue are disposed between adjacent vertebrae. The vertebrae provide support for the head and body, while the discs act as cushions. In addition, the spine encloses and protects the spinal cord, which is surrounded by a bony channel called the spinal canal. There is normally a space between the spinal cord and the borders of the spinal canal so that the spinal cord and the nerves associated therewith are not pinched.
Over time, the ligaments and bone that surround the spinal canal can thicken and harden, resulting in a narrowing of the spinal canal and compression of the spinal cord or nerve roots. This condition is called spinal stenosis, which results in pain and numbness in the back and legs, weakness and/or a loss of balance. These symptoms often increase after walking or standing for a period of time.
There are number of non-surgical treatments of stenosis. These include non-steroidal anti-inflammatory drugs to reduce the swelling and pain, and corticosteroid injections to reduce swelling and treat acute pain. While some patients may experience relief from symptoms of spinal stenosis with such treatments, many do not, and thus turn to surgical treatment. The most common surgical procedure for treating spinal stenosis is decompressive laminectomy, which involves removal of parts of the vertebrae. The goal of the procedure is to relieve pressure on the spinal cord and nerves by increasing the area of the spinal canal.
Interspinous process decompression (IPD) is a less invasive surgical procedure for treating spinal stenosis. With IPD surgery, there is no removal of bone or soft tissue. Instead, an implant or spacer device is positioned behind the spinal cord or nerves between the spinous processes that protrude from the vertebrae in the lower back. A well-known implant used for performing IPD surgery is the X-STOP® device, which was first introduced by St. Francis Medical Technologies, Inc. of Alameda Calif. However, implantation of the X-STOP® device still requires an incision to access the spinal column to deploy the X-STOP® device.
It would be advantageous to provide an implant for performing IPD procedures that could be percutaneously inserted into the interspinous process space and effectively treat lumbar spinal stenosis.